Flame retardancy, mechanical, and thermal properties of waterborne polyurethane conjugated with a novel phosphorous-nitrogen intumescent flame retardant

Abstract

A novel phosphorous‐nitrogen intumescent flame retardant with reactive diamino groups, benzoguanamine spirocyclic pentaerythritol bisphosphonate (BSPB), was synthesized and used as a chain extender, and then a series of flame retardant waterborne polyurethanes (FRWPU) were prepared by covalently conjugating the BSPB into waterborne polyurethane (WPU) backbone. Their structures were characterized by Fourier transformed infrared spectrometry (FTIR), 1H and 31P nuclear magnetic resonances (NMR), respectively. Simultaneously, the flame retardancy and the thermal stability of FRWPU were systematically investigated by limiting oxygen index (LOI) test, UL‐94 vertical burning test and thermogravimetric analysis (TGA). The results indicated that with the increase of BSPB content from 0 to 8 wt%, the LOI value of FRWPU increased from 18.6 to 27.3%, showing significant improvement by 8.7%. Compared with WPU, FRWPU showed decreased thermal stability but promoted char residue ratio. Conjugation of BSPB could obviously enhance the mechanical properties of FRWPU, the Young's modulus and tensile strength dramatically increased with the increase of BSPB. Investigation of char forming mechanism of BSPB through real time Fourier transform infrared spectra (RTFTIR) and scanning electronic microscopy (SEM) revealed that the polyphosphoric acid and phosphorus oxynitrides rich outer intumescent char layer could form protective shields to inhibit effectively internal polyurethane to heat and flame diffusion during contacting fire. POLYM. COMPOS., 38:452–462, 2017. © 2015 Society of Plastics Engineers

Preparation of poly(ether‐block‐amide)/poly(amide‐co‐poly(propylene glycol)) random copolymer blend membranes for CO2/N2 separation

“…. A group of peaks at 7.0–8.1 ppm are assigned to the aromatic protons of 9FDA and HFA . When the 1 H NRM spectrum of PA‐PPG random copolymers was compared with the 1 H NRM spectra of PA, PA‐PPG random copolymers appeared the two new peaks at 3.4 and 1.0 ppm that are respectively caused by CH* 2  and CH* 3 protons of PPG .…”

Synergistic Effects of Black Phosphorus/Boron Nitride Nanosheets on Enhancing the Flame-Retardant Properties of Waterborne Polyurethane and Its Flame-Retardant Mechanism

“…The peaks at 2250–2400 cm −1 , 2190 cm −1 and 1650–1810 cm −1 are related to CO 2 , CO, and carbonyl compound, respectively. The peak at 915 cm −1 corresponds to the bending vibration of the NH 3 , and peaks at 1320–1550 cm −1 refer to the stretching vibration of NO x (such as N 2 O, NO and NO 2 ) [ 46 ], indicating WPU combustion has two main stages: Before the combustion, the WPU decomposed to give flammable gases such as hydrocarbon and carbonyl compounds. With the increase of temperature, a large amount of combustible gas was ignited and the WPU began to burn violently.…”

Flame retardancy and thermal properties of rigid polyurethane foam conjugated with a phosphorus–nitrogen halogen-free intumescent flame retardant

“…Therefore, these phosphorous nitrogen flame retardants have been widely applied in polyurethane materials for flame retardancy. 17,18,63,64 In the next plan, we will design and synthesize HAPO to combine with inorganic flame retardants to form a synergistic system, hoping to achieve a flame-retardant effect similar to that of PDOP. 65,66…”